The ‘read *’ command reads everything from the pipe and the for loop will cut it into lines and run the loop for every entry. The line content is stored in ‘b’. To stop replacement of ‘$b’ by the shell itself (should be done later in the loop) you need to escape the ‘$’ character.

If you want to use a persistent bundle watch use the ‘mhu osgi tool’ called ‘bundle:persistentwatch’. You need to add the entries to the persistent list.